OXIDATION OF METHANOL BY FACULTATIVE AND OBLIGATE METHYLOTROPHS

  • 1 January 1976
    • journal article
    • research article
    • Vol. 23  (4) , 375-386
Abstract
The newly isolated methanol obligate Methylomonas sp. and the methanol facultative Pseudomonas sp. oxidize methanol at an unchanged rate over concentration range from 0.2-600 mM; the oxidation rate by the obligate methylotroph is 2.5 times higher (300 nmol O2/min per mg dry wt). Low-molecular alcohols, formaldehyde and formate serve as respiratory substrates for the intact cells of both methylotrophs. Methanol dehydrogenase of both methylotrophs isolated should be classified as the phenazine methosulfate-dependent pteridine-type enzyme of methanol- and formaldehyde-dehydrogenase function. This soluble enzyme is stimulated .apprx. 10-fold by NH4+, which results in enhancement of Vmax, and shows the same specificity and the same affinity toward methanol and formaldehyde (Km .apprx. 5 .times. 10-5 M). Heat-inactivation of the 10-fold purified enzyme is associated with the release of a watersoluble pigment with maximum fluorescence at 420-430 nm. NAD-dependent formate dehydrogenase catalyzed the 3rd step of methanol oxidation in both methylotrophs.

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